Sender Policy Framework, or SPF, is a verification system, which is designed to prevent the so-called email spoofing where an e-mail message can be sent from one address, but to seem as being sent from another, typically with the objective to fraud the recipient for some reason. When SPF protection is enabled for a domain name, an exclusive record is generated for it in the Domain Name System and all the DNS servers worldwide receive it. The record contains all email servers that are permitted to send legitimate messages from an e-mail address within the domain. When an e-mail is sent, the first DNS server it goes to verifies the SPF record and if the sending server is permitted, the message is forwarded to the targeted receiver. If, however, the sending server is not contained in the SPF record for the specified domain, the e-mail message will not be forwarded and it will be discarded. If you employ this solution, it will prevent third parties from sending spam messages which appear to have been sent by you.